Radeon HD 4870 512MB vs Radeon HD 7870

Intro

Compare all that to the Radeon HD 7870, which comes with core clock speeds of 1000 MHz on the GPU, and 1200 MHz on the 2048 MB of GDDR5 memory. It features 1280 SPUs as well as 80 TAUs and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 512MB		150 Watts
Radeon HD 7870		175 Watts
	Difference: 25 Watts (17%)

Memory Bandwidth

The Radeon HD 7870 should theoretically be a lot faster than the Radeon HD 4870 512MB overall. (explain)

Radeon HD 7870		153600 MB/sec
Radeon HD 4870 512MB		115200 MB/sec
	Difference: 38400 (33%)

Texel Rate

The Radeon HD 7870 should be much (about 167%) better at AF than the Radeon HD 4870 512MB. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon HD 4870 512MB		30000 Mtexels/sec
	Difference: 50000 (167%)

Pixel Rate

The Radeon HD 7870 should be much (approximately 167%) faster with regards to AA than the Radeon HD 4870 512MB, and should be capable of handling higher resolutions better. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon HD 4870 512MB		12000 Mpixels/sec
	Difference: 20000 (167%)

Please note that the above 'benchmarks' are all just theoretical - the results were calculated based on the card's specifications, and real-world performance may (and probably will) vary at least a bit.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the max amount of data (measured in megabytes per second) that can be transported past the external memory interface within a second. It's worked out by multiplying the card's bus width by its memory speed. In the case of DDR RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied per second. This number is worked out by multiplying the total number of texture units by the core clock speed of the chip. The higher the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly write to the local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the number of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.